1. Field of the Invention
The present invention relates to a semiconductor transistor, and more particularly to a silicon-compatible germanium-based high-hole-mobility transistor (HHMT) with high-hole-mobility.
2. Description of the Related Art
Throughout the history of semiconductor transistor development, a large number of high-electron-mobility transistors (HEMTs) using high-electron-mobility have been studied actively, but only a few high-hole-mobility transistors (HHMTs) with high-hole-mobility are studied.
This is because a large number of semiconductor materials having high-electron-mobility are present, but the semiconductor materials having high-hole-mobility are extremely rare.
Germanium has recently been studied for implementing germanium-based p-type metal-oxide-semiconductor field effect transistors (MOSFETs) due to its intrinsically high-hole-mobility. However, there have been a complexity of the manufacturing processing and a limitation of techniques for getting enough high hole mobility of germanium because of a high channel doping concentration required inevitably in a highly scaled channel.
For example, Korean Patent Nos. 10-0585111 and 10-0644811 disclose techniques for getting carrier mobility of channel higher than that of silicon by forming a germanium channel region. However, there have been such problems that it is difficult to form an oxide film as a gate insulating film on a germanium channel region unlike silicon and to get enough high hole mobility of a germanium channel because of a carrier scattering and the like at the interface between an oxide film and a germanium channel though the gate insulating film being formed of any oxide on the germanium channel region.